1. Field of the Invention
This invention relates generally to the field of wireless communications. In particular, the invention relates to wireless communication systems capable of receiving both digital satellite radio and Global Positioning Systems (“GPS”) signals.
2. Related Art
The worldwide utilization of wireless devices such as two-way radios, portable televisions, Personal Digital Assistants (“PDAs”) cellular telephones (also known a “mobile phones”), satellite radio receivers and Global Positioning Systems (“GPS”), also known as NAVSTAR, is growing at a rapid pace. As the number of people employing wireless devices increases, the number of features offered by wireless service providers also increases, as does the integration of these wireless devices in other products. As an example, the present trend in the automobile and truck industry is to produce automobiles and trucks that have amplitude modulation (“AM”), frequency modulation (“FM”), phase modulated (“PM”), short-wave (“SW”) and single-side band (“SSB”) radios, mobile phones, GPS receivers, digital radios (also known as digital audio broadcasting “DAB” systems) and satellite radios (also known as digital satellite radios, or “DSRs,” that receive programming from service providers such as, for example, Sirius Satellite Radio, XM Satellite Radio, Orbit Satellite Television and Radio Network, and WorldSpace Corp.) The recreational ship, boat and airplane industries are also following the same trend as the automobile and truck industry. Additionally, integration in wireless devices is occurring with the mobile phone industry integrating GPS capabilities within the mobile phones to meet the Enhanced 911 (also known as “E911”) services mandated by the United States Congress.
As these wireless devices are integrated into products such as automobiles, ships, boats, airplanes, motorcycles, other transportation products and mobile phones, the cost and complexity of producing these products also increases along with the space requirements with a vehicle. Therefore, a goal of these industries includes producing these products with integrated wireless devices that have the highest performance at the lowest implementation cost.
As in many other areas of electronics, in order to minimize the implementation cost, retain a desired performance, and reduce component size, designers usually attempt to maximize the level of integration, minimize the complexity and minimize any adjustments that may be required (such as tuning). Unfortunately, the radio frequency “RF,” intermediate frequency “IF,” and baseband portions of a wireless device are usually the most difficult to implement with high levels of integration, reduced complexity and minimal, or no, tuning.
Additionally, all known implementations of wireless devices such as radio receivers (whether AM, FM, PM, SW, SSB, DAB and/or DSR) and GPS receivers utilize a separate path for each RF radio band received. For example, in current wireless systems the ability to receive GPS signals is accomplished with GPS receiver circuitry, and the ability to receive DSR signals is accomplished with DSR circuitry separate from the GPS receiver circuitry. As a result, these current wireless systems have system architectures that typically include multiple mixers, components that utilize IF frequencies in the down conversion process of the signal, double down conversion circuitry, and external components that include RF and IF filters, coils and transformers. Examples of these type of implementations include the following GPS and radio chipsets: Conexant 6732, third generation Gemini/Pisces solutions, owned by SiRF Technology, Inc., San Jose, Calif., GPS architectures utilizing Colossus RF ASIC by Trimble, PVT-6 receiver and RF chip MRFIC 1504, by Motorola, Inc., Schaumburg, Ill., BT1575A GPS receiver by BethelTronix Inc, Cerritos, Calif., PCS and GPS receiver RFR3300 and IRF 3300 by Qualcomm, Inc., San Diego, Calif., UPB1005GS by NEC, Corp, Japan, and CXA1951AQ by Sony, Inc., Japan.
Therefore, there is a need for a system and method that allows GPS and radio (such as AM, FM, SW, SSB, DAB and/or DSR) signals to be received utilizing the same receiver circuitry. Additionally, there is also a need to enhance the performance of the system, reduce the system cost, reduce and/or eliminate any tuning required and reduce the utilization of external components.